1. Field of the Invention
The present invention is directed to a monitoring system and method for operating the system including a reading device in wired communication with a probe. In particular, the present invention is directed to a monitoring system in which the reading device is in wired communication with a probe having a memory device embedded therein to prohibit being separated from a sensor by the user during use.
2. Description of Related Art
Medical probes comprising one or more physiological sensors or transducers are used to measure parameters such as, but not limited to, pressure, tension or displacement. Such probes may be external to the body or implantable within the body. Some sensors or transducers such as pressure sensors are typically designed as a resistive bridge balancing circuit (e.g., a Wheatstone bridge). When using a sensor or transducer a non-volatile read/write memory may be required to store data such as calibration parameters (e.g., zeroing, temperature coefficient), information associated with a patient (e.g., age) and/or equipment information (e.g., probe expiration date, probe usage time and/or failure mode information (for instance, recovery data in case of memory corruption)). As an illustrative example, the medical probe may be a differential pressure sensor for measuring intracranial pressure (ICP) within the brain. In such application, prior to implantation of a device (e.g., implantable ICP solid state sensor) an ambient pressure reference value, also referred to as “zero reference value” or “offset reference value,” is detected and stored in a memory. Typically, the zero or offset pressure reference value is measured when the sensor is wet by soaking the tip in a shallow pool of sterile water or sterile saline for a predetermined period of time (e.g., approximately 15 minutes to approximately 30 minutes). Alternatively, the zero or offset reference value (e.g., offset pressure value) may be measured in air. During use, each measurement value detected by the sensor is compensated or offset by the previously calibrated offset reference value to produce a compensated value.
Reading of information from or writing of information to the memory device associated with the probe by a separate reading device occurs via a communication interface (e.g., wireless or wired). A wireless communication interface using such technology as bar code scanning is limited to reading information stored in the memory associated with the probe. Writing or storing of new information to the memory device is not permitted with bar code scanning. Other commonly used wireless technology such as Radio Frequency Identification (RFID) disadvantageously increases the overall complexity due to the additional circuitry and components required.
Alternatively, a wired connection via an interface cable may be used to transmit information to and from the reading device, wherein the probe and a memory device are embedded within the interface cable itself. The zero or offset reference value stored in memory must undesirably be reentered/acknowledged whenever interface cables used to connect the probe to the reading device are replaced or even when the same interface cables are used to reconnect the probe to the reading device. Furthermore, a reusable interface cable that requires sterilization, (e.g., autoclaved), may possibly result in physical damage to the memory. Thus, embedding of the memory device in the interface cables disadvantageously permits the memory device to be separated from the probe itself. For either a reusable or one-time-usage probe capable of being powered off or disconnected while in use, it is preferable that separation of the memory from the probe by the patient while in use be prohibited in order to: (i) avoid the possibility of crossing the probe with a memory associated with a different probe and thus avoid the use of wrong data; (ii) retain data stored within the memory device even in the absence of power; and (iii) reduce complexity of confirming the zero value associated with a probe.
It is therefore desirable to develop a probe with a memory device embedded therein that prohibits separation by the user during use while simultaneously minimizing the overall footprint of the probe and the number of wires/lines/electrical connections between the probe and a separate reading device.